1. Field of the Invention
The present invention relates to a sheet-speed reduction mechanism for a fan wheel by which mechanism the speed of a signature transported from a folder of a printing press is reduced before the signature is held in the fan wheel.
2. Description of the Related Art
A web-fed rotary printing press is provided with a folder for forming a signature (sheet) from a web. The web is dried and cooled after a print is made thereon, and thereafter the folder cuts the web into pieces each having a predetermined length. The folder then folds each piece of the web along the width direction, or along the longitudinal direction, of the piece, so that the signature is formed. The signature thus folded by the folder is delivered to the outside of the printing press by a delivery device which is provided at the most downstream side, in a direction in which the signatures (web) are transported (hereinafter, referred to simply as the signature transporting direction), in the folder.
The signatures are transported at predetermined intervals to the delivery device. The delivery device grabs the signatures between fan blades of a rotating fan wheel one by one, thus holding the signatures therebetween. The delivery device then discharges the signatures onto a delivery conveyor disposed below the fan wheel. In this way, the signatures are placed at predetermined intervals on the delivery conveyor to be eventually delivered to the outside of the printing press.
In the above-described fan wheel, the movement of each signature advancing between the fan blades is firstly restricted, at the front end thereof, by a stopper, so that the signature is held by the stopper. Then, the signature is gradually discharged from between the fan blades in association with the rotation of the fan wheel. Thereafter, the signature is finally transferred almost horizontally onto the delivery conveyor. Such a fan wheel of the conventional delivery device is disclosed, for example, in Patent Document 1.
<Patent Document 1>
    Japanese Patent Application Publication No. Hei. 11-11769
However, in such conventional fan wheel, a signature slid between the fan blades is caused to hit the stopper at the same speed as the sliding speed of the signature into the fan wheel. For this reason, the front end of the signature may be damaged or deformed. In addition, the signature may be caused to bounce off when hitting the stopper, thus protruding from the fan wheel. In this case, the signature may be brought into contact with a peripheral component of the fan wheel, thus being bent or stuck therein. As a result, the attitude of the signature in the fan wheel becomes unstable. If the signature is discharged onto the delivery conveyor in this unstable state, the following problem may occur. Specifically, a signature may be caused to overlap the preceding one, so that the intervals for the transport may become non-uniform. In addition, if a signature is bent or displaced, the accuracy in the delivery may be adversely affected.